Surecast never felt like a decent tool back pre-Stormblood, this much I think most can agree on. It had its uses, but they were niche to say the least. So when I read that it was changed to make you resist knockback and draw-in as well like Tempered Will (and now Arm's reach), I thought about trying it (more like abusing it) as soon as I started leveling BLM. Sirensong Sea, very first boss, no dice. So I guess it DOES NOT work against all knockbacks and draw-ins. Still gotta experiment on most bosses (primarily endgame, still need to set foot in EX), as of right now it only worked against Landslides and Bardam's Mettle final boss.
Plus it doesn't really help that the buff disappears as soon as you start casting, making it even less useful- you still lose some measure of uptime, regardless if you stay still or you cast after you activate SC. You can't use it to cast during a Tidal Wave, for example - you gotta stay still for the attack to go off before you start casting again.
So I ask: what's the point of a skill that is supposed to allow you to cast a single spell uninterrupted and resist knockback/draw-ins, but the latter only applies if you aren't casting a spell? What are your thoughts on the matter?